Study On The Dynamic Process Of Hot Carriers In Two Dimensional Heterojunction Materials

Nowadays,with the depletion of fossil fuels and the growing importance of environmental protection,solar energy has attracted much attention because of its accessibility and pollution-free nature.The photoelectric conversion efficiency of solar energy is an important factor affecting the performance of photoelectron.However,the loss of energy associated with hot carriers during the recombination process will greatly hinder the photoelectric conversion efficiency of photovoltaic devices.Therefore,in order to improve the photoelectric conversion efficiency,we consider the effective separation of charges to inhibit the recombination of hot carriers.This paper,by using the density functional theory and non adiabatic molecular dynamics method to study the two-dimensional van der Waals heterojunction Phosphorene/HfS2 and hot carrier dynamics process of InSe/Sb.The effects of non-adiabatic coupling strength,the energy level difference and dephase time on hot carrier relaxation time were expiored.The specific results of the research are as follows:?1?We studied the hot carrier dynamics of Phosphorus/HfS₂,found by calculation,Black Phosphorus/HfS₂ is the type-?band arrangement semiconductors with direct band gap.The main factors affecting the relaxation rate of hot carriers in Phosphorene/HfS₂ are the the non-adiabatic coupling,band gap and the dephasing time.In the process of study,we found that the non-adiabatic coupling of the conduction band is slightly better than that of the valence band and band gap of the conduction band is slightly smaller than the valence band,but the dephasing time of the conduction band is much slower than that of the valence band.?2?We explored the van der Waals heterojunction InSe/Sb in the relaxation process of hot carrier.By comparing the relaxation time of hot electrons and hot holes,it is found that the relaxation speed of hot electrons is faster.The study found that the main reason for the faster decay of the hot electrons is that the NA coupling of the conduction band is stronger than that of the valence band.The dephasing time of the conduction band is longer than that of the valence band and the conduction band has a small band gap.Our results demonstrate the two-dimensional van der Waals heterojunction Black Phosphorus/HfS₂ and InSe/Sb are potential materials for future optoelectronic applications.